Almost starting to sound like a hardware issue.
Did you update the bios firmware? Is your laptop new or old?
If new bring it back and get it fixed or exchanged.
If old then you maybe out of luck if some controler chips are fried if you can't see HDDs or CDs.
Or you changed something in the bios settings and removed the HDD as an active device.
in your first post it looks like corrupt HDD. Scandisk can work if you have an old 98 sec floppy boot disk.
Try here.
http://www.bootdisk.com/
Or try your luck with HP
http://welcome.hp.com/country/ca/en/...isplay=support
Good luck dude.